Cool, clean, unimpeded air flow is exactly what an engine needs to give it's best performance. Perhaps it is time for a close inspection of the air-filter assembly and inlet tracts? Look for cracks in the air-filter case, ruptures or partial blockages in the hoses and particulates attached to the inlet tracts spoiling air-flow to the carburettor/s. And, of course, renew the air-filter cartridge without fail.
This component and perhaps some of those below maybe required?
Add as many air-filter and intake components(or anything else you fancy for that matter) as you wish to the same shopping cart, new blind plugs 16G1356900 clips 90467100399046711106 and seal 4NK1445200 for example, and still only pay the same single fixed price shipping cost.
This part may have other applications within the Yamaha model range.